Streamflow

• What is stream stage?


  It refers to how high the water surface is above a predefined elevation point in the stream.
• How is stream stage typically defined?


  Stream stage is defined as the height of the water surface above a predefined elevation point, often the streambed.
• What does streamflow measure?


  Streamflow measures the volumetric rate of flow of water in an open channel.
• What factors are included in the definition of streamflow?


  Streamflow includes the volume of water per unit time, sediment, and other solids mixed with it.
• What is the formula for calculating discharge using the float velocity method?


  • Discharge (Q) = Vsurface * A
  • Where Vsurface = flow velocity at the water surface
  • A = water cross-sectional area
• Given a trapezoidal channel with a bottom width of 2.0 m, side slope of 1:1, and bottom slope of 0.001, how would you calculate discharge using the float velocity method?


  Use the average travel time and distance to find the flow velocity, then multiply by the cross-sectional area.
• What is the formula for the slope-area method?


  Δh = drop in water surface level, L = distance along the channel stretch.
• What does Manning's equation relate to in open channel flow?


  Manning's equation relates average flow velocity, roughness coefficient, hydraulic radius, and slope of the channel.
• How do you calculate the hydraulic radius (R) in Manning's equation?


  R = A / P, where A is the cross-sectional area and P is the wetted perimeter.
• What is the average flow velocity (Vave) for a one-point measurement?


  VAVE = V0.6d, where V0.6d is the current velocity at 0.6d below the water surface.
• How is average flow velocity calculated for a two-point measurement?


  Vave = (V0.2d + V0.8d) / 2, where V0.2d and V0.8d are current velocities at 0.2d and 0.8d below the surface.
• What is the purpose of the current meter method?


  The current meter method measures the velocity of the stream.
• What are the methods of flow measurement?

  • Current meter method
  • Float velocity method
  • Slope-area method
  • Use of discharge measurement structures
• What is stream gauging?


  Stream gauging is measuring the discharge rate of a stream.
• How is runoff determined from a catchment area?


  Runoff is determined by measuring the discharge of the stream draining the catchment.